Bt insecticide technology is exquisite.

Bt insecticide, that is, Bacillus thuringiensis microbial insecticide, has been widely used to control crop pests because it is safe, harmless to natural enemies and difficult to develop resistance to pests. In practical application, because some farmers have not mastered the method, the effect is not satisfactory. The use of bt pesticides, there are a lot of technical attention, farmers should master. Master the reasonable application concentration. Different species of pests have different sensitivity to bt insecticides, so the application concentration is different. Only by selecting the appropriate concentration according to the sensitivity of pests can a good control effect be obtained. For example, 500-1000 times dilution can be used for sensitive pests such as rice bract, rice leaf roller, cabbage worm and so on. For less sensitive pests such as Chilo suppressalis and Helicoverpa armigera, 100-200 times dilution should be used. Choose to apply it under suitable conditions. The spores of bt insecticide had the highest activity and the best application effect when the temperature was 20: 25 ℃ and the relative humidity was more than 85%. Under the environmental conditions such as temperature below 20 ℃, long-time sunlight, strong wind and rainstorm, the activity is low, and the application effect is poor, so it is necessary to avoid these adverse weather conditions. When the strong light and temperature are above 25 ℃, it is appropriate to apply it at about 5 pm, and it can be applied all day in cloudy days. When spraying, the bottom and back of the leaves should be sprayed thoroughly in order to improve the efficacy. Powder should be applied after dew or light rain in the morning and evening to facilitate the drug to adhere to crop stems and leaves and play a toxic role. Determine the appropriate application time. The efficacy of bt insecticides is slower than that of chemical insecticides, and the application time should be 2-3 days earlier than that of chemical insecticides, and the effect is the best from the egg incubation period to the first instar larva stage. Mixed with chemical pesticides. In order to improve the control effect of insecticides, especially in the occurrence of major pests and mixed occurrence of many kinds of pests, it should be mixed with chemical insecticides such as dimethophos, dimethamidophos, triazophos, dichlorvos, trichlorfon and so on. If bt emulsion is used alone, with 200 ml per mu, the control effect on rice leaf roller is only 70%-80%, and that on Chilo suppressalis is only 60%. If 100ml of bt emulsion and 100ml of 18% insecticidal double water agent are used per mu, the control effect on rice leaf roller can reach about 95%. With 200ml bt emulsion and 100ml Shachongshuang per mu, the control effect on Chilo suppressalis can reach 95%. At present, the pesticides sold in the market, such as Bishuangling, green borer killing, special killing borer, must kill borer and so on, are all bt powder or emulsion mixed with insecticidal single powder or insecticidal double water agent, which should be preferred.